The immediate objectives of this research are to determine the arrangement of translated, transcribed and repetitive sequences in a variety of cloned segments of D. melanogaster chromosomal DNA (Dm segments) containing specific genes. By mapping the transcribed and translated sequences we anticipate determining the boundary conditions for the processing events whereby primary transcripts are converted to functional RNAs (e.g., mRNAs, tRNAs, etc.). Similarly these mapping experiments provide for the identification of promoter sites and allow one to define the sequences present in and neighboring the promoter -i.e.., the sequences that are involved in the regulation of transcription. In particular, we wish to know whether the clusters of moderately repetitive sequences that are distributed throughout most of the genome play a role in this regulation. Our recent experiments indicate that these clusters individually consist of several different repetitive sequences, and that different clusters contain different combinations of these sequences; i.e., one cluster may consist of R3:R6:R2:R9, and another of Rl:R6:R2:R7, etc. While this arrangement is consistent with certain regulatory models, we wish and have yet to determine whether such clusters contain or are directly linked to promoter sites, and if so, whether their function is regulatory. BIBLIOGRAPHIC REFERENCES: Hogness, D.S., P.C. Wensink, D.M. Glover, R.L. White, D.J. Finnegan, and J. E. Donelson (1975). "The Arrangement of DNA Sequences in the Chromosomes of Drosophila melanogaster". In The Eukaryote Chromosome, ed. by W. J. Peacock and R.D. Brock. Australian National University Press, Canberra. pp.1-33. This article was listed previously as in press, because it was anticipated that publication would be in 1974. As the book was instead published in 1975, it is listed here. Glover, D.M., R.L. White, D.J. Finnegan and D.S. Hogness (1975). "Characterization of Six Cloned DNAs from Drosophila melanogaster, including one that contains the genes for rRNA". Cell 5, 149-157.